U.S. patent number 6,516,506 [Application Number 09/779,775] was granted by the patent office on 2003-02-11 for installing a scrolled resilient sheet alongside the inner surface of a fluid conduit.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Martin Donnelly, Wilhelmus Christianus Maria Lohbeck, Robert Bruce Stewart.
United States Patent |
6,516,506 |
Donnelly , et al. |
February 11, 2003 |
Installing a scrolled resilient sheet alongside the inner surface
of a fluid conduit
Abstract
A scrolled resilient sheet is installed against the inner
surface of a fluid conduit using a carrier tool from which a
resilient sheet having an average thickness more than 2 mm and an
elastic or pseudoelastic recoverable strain of at least 0.6% is
released so that the sheet expands with an expansion force which is
sufficiently high to allow the sheet to press itself into place
alongside the inner surface of the conduit and to remain in place
after installation.
Inventors: |
Donnelly; Martin (Amsterdam,
NL), Lohbeck; Wilhelmus Christianus Maria (Rijswijk,
NL), Stewart; Robert Bruce (Rijswijk, NL) |
Assignee: |
Shell Oil Company (Houston,
TX)
|
Family
ID: |
8229482 |
Appl.
No.: |
09/779,775 |
Filed: |
February 9, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
140938 |
Aug 27, 1998 |
|
|
|
|
Foreign Application Priority Data
|
|
|
|
|
Aug 27, 1997 [EP] |
|
|
97306555 |
|
Current U.S.
Class: |
29/451; 138/97;
166/207; 264/269; 29/402.09; 166/277 |
Current CPC
Class: |
E21B
29/10 (20130101); E21B 43/086 (20130101); E21B
43/103 (20130101); F16L 55/163 (20130101); E21B
43/108 (20130101); Y10T 29/49732 (20150115); Y10T
29/49872 (20150115); Y10T 29/4987 (20150115) |
Current International
Class: |
E21B
29/10 (20060101); E21B 43/08 (20060101); E21B
43/02 (20060101); E21B 43/10 (20060101); F16L
55/163 (20060101); F16L 55/162 (20060101); E21B
29/00 (20060101); B23P 011/02 (); E21B 029/00 ();
F16L 055/18 () |
Field of
Search: |
;29/402.09,450,451,458
;138/97,98 ;166/207,277 ;264/269,516 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2-164952 |
|
Jun 1990 |
|
JP |
|
1810482 |
|
Apr 1993 |
|
SU |
|
Primary Examiner: Bryant; David P.
Parent Case Text
This is a continuation of application Ser. No. 09/140,938 filed
Aug. 27, 1998, now abandoned the entire disclosure of which is
hereby incorporated by reference.
Claims
We claim:
1. A method for installing a scrolled resilient sheet alongside the
inner surface of a fluid conduit, the method comprising the steps
of: scrolling the resilient sheet and securing the scrolled sheet
to a carrier tool such that the carrier tool carrying the scrolled
sheet can be moved through the conduit; moving the carrier tool to
a location in the conduit where the resilient sheet is to be
installed; and releasing the resilient sheet from the carrier tool
thereby allowing the resilient sheet to expand towards the inner
surface of the conduit,
wherein the resilient sheet has an average wall thickness of at
least 2 mm and an elastic strain or a pseudoelastic recoverable
strain of at least 0.6% so as to induce the scrolled sheet to
expand with an expansion force which is sufficiently high to allow
the sheet to press itself into place alongside the inner surface of
the conduit during installation and to remain in place after
installation with no further means of securing the sheet in
place.
2. The method of claim 1, wherein the resilient sheet has an
average wall thickness of at least 3 mm and is made of a titanium
alloy having an elastic modulus not more than 115.000 MPa and a
proof stress of at least 825 MPa.
3. The method of claim 2, wherein the resilient sheet material has
an average wall thickness of at least 4 mm and is made of a
Ti-6Al-4V alloy.
4. The method of claim 1, wherein the fluid conduit is formed by an
inflow region of hydrocarbon production well and the sheet is
perforated at regular intervals and is installed alongside the
inner surface of the wellbore to serve as a wellscreen.
5. The method of claim 4, wherein the perforations consist of
elongate circumferential slots which are arranged in substantially
parallel rows both axially and circumferentially across the sheet,
with no stagger between the rows of slots.
6. The method of claim 4, wherein the perforations are tapered in
radial direction such that the smallest width of the perforations
is located at the outer surface of the scrolled resilient
sheet.
7. The method of claim 1, wherein the resilient sheet has a
thickness of at least 5 mm and is made of a pseudoelastic
alloy.
8. The method of claim 7, wherein the alloy is solution-treated
Ti-16V-3Al-6Zr.
9. The method of claim 7, wherein the alloy is TiNi.
Description
BACKGROUND OF THE INVENTION
The invention relates to a method for installing a scrolled
resilient sheet alongside the inner surface of a fluid conduit.
It is known from U.S. Pat. Nos. 4,501,327 and 5,040,283 to scroll a
sheet around a carrier tool and then move the carrier tool carrying
the scrolled sheet through the conduit towards a location where the
resilient sheet is to be installed, whereupon the sheet is released
from the carrier tool and allowed to expand towards the inner
surface of the conduit.
U.S. Pat. No. 5,040,283 employs a sheet made of a memory metal
which expands as a result of a temperature increase. A drawback of
this method is that memory metals are expensive and are not readily
available in large sheets.
U.S. Pat. No. 4,501,327 discloses the use of spring steel or
aluminum as a resilient material, which materials have an elastic
strain which is 0.55% or less (0.2% for aluminum) and that a
suitable thickness for the sheet material is approximately 3/64
inch (=1.2 mm).
In this known method the resilient material is pressed against the
wall of the conduit when the carrier tool is pulled back through
the expanded sheet.
Drawbacks of this known method are that a relatively thin sheet
material is used which can be easily damaged and which has a
resiliency which is only sufficient to unscroll the sheet but which
does not induce the sheet to press itself into place alongside the
inner wall of the conduit so that a final pressing step is still
required.
It is believed that the low wall thickness of the known aluminum or
spring steel sheets and the relatively low expansion force are
associated with the low elastic strain capacity of the materials
used.
It is an object of the present invention to eliminate these
drawbacks and to provide a method for installing a scrolled
resilient sheet alongside the inner surface of a fluid conduit
which allows the use of a relatively thick and robust sheet which
is not easily damaged after installation and which does not require
the-step of pressing the sheet alongside the wall of the conduit by
means of an expansion tool.
SUMMARY OF THE INVENTION
Toward providing these and other advantages the method according to
the present invention employs a resilient sheet which has an
average wall thickness of at least 2 mm and an elastic or
pseudoelastic recoverable strain of at least 0.6% so as to induce
the scrolled sheet to expand with an expansion force which is
sufficiently high to allow the sheet to press itself into place
alongside the inner surface of the conduit during installation and
to remain in place after installation.
When used in this specification the term elastic strain refers to
the yield stress-Young's modulus ratio for materials which have a
yield point, like many carbon steels have, or the proof
stress-Young's modulus ratio for materials which do not have a
yield point. If the elastic strain is expressed as a percentage
then said ratio's are to be multiplied by a factor of 100.
Preferably the resilient sheet has an average wall thickness of at
least 3 mm and is made of a titanium alloy having an elastic
modulus not more than 115.000 MPa and a proof stress of at least
825 MPa, so that the elastic strain is more than 0.75%.
It is also preferred that the resilient sheet material has an
average wall thickness of at least 4 mm and is made of a Ti-6Al-4V
alloy.
The sheet may be a rectangular sheet without perforations which is
used to provide a seal or a patch of an area where the wall of the
conduit has been ruptured, damaged or eroded. Alternatively the
fluid conduit is formed by an inflow region of a hydrocarbon
production well and the sheet is perforated at regular intervals
and is installed alongside the inner surface of the wellbore to
serve as a wellscreen.
If the sheet is to be scrolled to a very small diameter, for
example if it is to be moved through constrictions in the conduit,
then it can be beneficial to use a pseudoelastic alloy as sheet
material. Suitable pseudoelastic alloys are Ti-16V-3Al-6Zr and
TiNi.
BRIEF DESCRIPTION OF THE DRAWINGS
These and further features, objects and advantages of the method
according to the invention will be more fully appreciated by
reference to the following detailed description of a preferred
embodiment of the invention which should be read in conjunction
with the accompanying drawings in which:
FIG. 1 is a schematic side elevational view of a resilient sheet
which is being placed inside a conduit in the form of a vertical
underground borehole; and
FIG. 2 is a side view of an unscrolled resilient sheet which
comprises circumferiential slots so that the sheet can be used as a
wellscreen.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1 there is shown a vertical wellbore 1
traversing an underground formation 2 and a resilient sheet 3 which
is unscrolling itself against the wall 4 of the wellbore 1.
The sheet 3 has been lowered into the wellbore 1 using a carrier
tool 5 which is suspended on a wireline 6.
The carrier tool 5 and wireline 6 are shown in the drawing in
dotted lines.
Before lowering the carrier tool 5 into the wellbore 1 the sheet 3
is scrolled around the tool 5 and fixed to the tool 5 using tack
welds and/or clips. When the tool has arrived at the location where
the sheet 3 is to be installed the tack welds and/or clips are
released, for example using explosive devices which shear off the
tack welds and/or clips.
The resilient sheet 3 has a thickness of at least 2 mm and an
elastic strain of at least 0.6% which allows the sheet to develop a
high expansion force so that it expands and presses itself into
place against the wall 4 of the wellbore 1 and to remain in place
after installation even if the pore pressure of the surrounding
formation 2 is higher than the fluid pressure within the wellbore
1.
When seen in circumferential direction, the ends of the resilient
sheet 3 form flaps 7 where the sheet 3 has a reduced wall
thickness. The circumferential length of the sheet 3 will be chosen
slightly larger than the circumference of the wall 4 of the
wellbore 1 such that the flaps 7 will at least partly overlap if
the resilient sheet 3 has been expanded against said wall 4. Thus
the flaps 7 will create a shut-off for leaks and will create a
smooth and almost seamless internal bore of the expanded sheet 3.
To improve the sealing a further sleeve (not shown) of cellular
rubber may be placed outside the outer flap 7. This sleeve should
be bonded along an axial line, but not around the circumference of
the flap 7. This is because the rubber has to stretch on
unscrolling, and must therefore slide over the flap 7 which does
not stretch. The interface may be lubricated.
In the assembly shown in FIG. 1 the flaps 7 are not taken into
account for determination of the average wall thickness of the
sheet 3. In accordance with the invention the average wall
thickness of the sheet 3 is at least 2 mm whereas the wall
thickness of the flaps 7 may be less than 2 mm. Thus, when used in
this specification, the term average wall thickness of the sheet
denotes the wall thickness of any parts of the sheet 3 other than
the flaps 7 and locations where the sheet 3 is perforated.
The maximum average wall thickness T of a sheet 3 that will fully
elastically unscroll can be estimated on the basis of the
formula:
where: d=the scrolled diameter of the sheet D=the relaxed diameter
of the sheet Y=the yield or proof stress of the sheet material; and
E=the elastic modulus of the sheet material. By virtue of its high
elastic strain, viz. at least 0.6% resulting from the combination
of low elastic or Young's modulus (preferably not more than 115.000
MPa) and high proof stress (preferably at least 825 MPa) the sheet
according to the invention can have larger wall thickness than
conventional resilient sheets. Titanium alloys having an elastic
modulus less than 150.000 MPa are particularly suitable for use in
the sheet according to the invention. A Ti alloy grade 5 sheet
having an average wall thickness of 4 mm can be used for a 7" (17.5
mm) casing repair. A Ti-22V-4Al alloy sheet having an elastic
modulus of 82 MPa and thermomechanically processed to achieve a
proof stress of 720 MPa or greater can be used for the same repair
with an average wall thickness of 5 mm.
Further, some metastable beta-titanium alloys such as
Ti-16V-3Al-6Zr with appropriate thermomechanical processing exhibit
pseudoelasticity to an extent that would permit an average wall
thickness between 11 and 13 mm. TiNi would permit even greater wall
thickness. These pseudoelastic alloys can also be used to permit
scrolling to a smaller diameter when the sheet has an average wall
thickness of several millimeters to allow installation through
constrictions, such as through-tubing operations in an oil or gas
production well.
The large average wall thickness of the sheet 3 is not only useful
for creating a robust scroll but also for enhancing the spring
force with which the sheet 3 unscrolls and presses itself against
the wall 4 of the wellbore 1.
Referring now to FIG. 2 there is shown a view of an unscrolled
sheet according to the invention where the sheet forms a well
screen 10 which contains elongate circumferential slots 11 that are
arranged in substantially parallel rows both axially and
circumferentially across the screen 10, with no stagger between the
rows of slots. The perforations are also tapered (not shown) in
radial direction so that the smallest width of the perforations is
located at the outer surface of the sheet when the sheet is
scrolled.
The tapered shape of the slots 11 serves to avoid that sand
particles which may enter the slots 11 could become stuck partway
in the slots 11.
Circumferential unstaggered slots 11 are preferred to holes or
non-circumferential slots because the operation of scrolling and
unscrolling can be performed with minimal stress concentrations in
the screen material, while retaining maximum spring force, strength
and stiffness.
The scrolled wellscreen shown in FIG. 2 can also be covered,
preferably at the outer surface, with filter material. Optionally
the filter material can be separated from the surface of the screen
10 by a drainage layer, for example coarse woven wire, so that the
fluid passing through the filter layer not immediate opposite a
slot 11 in the scroll can flow to the slot 11 through the drainage
layer.
The filter and drainage layers can be made of scrolled sheets of
filter and drainage material which surround the screen 10. The
sheets of the screen 10 and of the filter and drainage layers can
be provided with end flaps where the sheet has reduced thickness in
the same way as shown in FIG. 1 in order to create a seamless
screen when the assembly of the screen 10 and surrounding filter
and drainage layers unscrolls itself against the wellbore or
perforated production liner. The wellscreen can thus press itself
directly against the wellbore or perforated production liner,
without an intervening annulus, thus obviating the need for gravel
packing, thereby reducing the risk of erosion and stabilizing the
formation.
If desired, the overlapping ends of the sheet or screen may be
maintained in a fixed position relative to each other once the
sheet has been expanded and installed within the conduit or
wellbore. This may be achieved by welding or bonding the ends to
each other, or by providing the overlapping ends with axial locking
grooves or with ratchet profiles that allow unscrolling but prevent
re-scrolling of the sheet or screen.
* * * * *